Apparatus And Methods For Trans-Septal Retrieval Of Prosthetic Heart Valves

ABSTRACT

In some embodiments, a method for transfemoral retrieval and/or repositioning of a prosthetic valve implanted within a heart includes inserting a retrieval assembly through a femoral vein and into a heart until a distal end portion of the retrieval assembly is disposed in an atrium of the heart. The prosthetic valve is formed with a shape-memory material. The retrieval assembly includes an outer catheter, a middle catheter, a snare catheter, and a snare member. The snare member is moved distally out of a lumen of the snare catheter and into engagement with an inner frame of the prosthetic valve. The retrieval assembly can invert an outer frame of the prosthetic valve to collapse and retract the valve into a lumen of the retrieval assembly. In some embodiments, a positioning catheter can be inserted through the apex of the heart to assist in positioning and inverting the prosthetic valve.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No. 16/316,102, filed on Jan. 8, 2019, which is a national phase entry under 35 U.S.C. § 371 of International Application No. PCT/US2017/041454 filed Jul. 11, 2017, published in English, which claims priority to and the benefit of U.S. Provisional Patent Application No. 62/361,228, entitled “Apparatus and Methods for Trans-Septal Retrieval of Prosthetic Mitral Valves,” filed Jul. 12, 2016, the disclosures of which are incorporated herein by reference in their entireties.

BACKGROUND

Embodiments are described herein that relate to devices and methods for use in the retrieval of prosthetic valves, and particularly to devices and methods for trans-septal retrieval of expandable prosthetic mitral valves.

Prosthetic heart valves can pose particular challenges for delivery and deployment within a heart. Valvular heart disease, and specifically, aortic and mitral valve disease is a significant health issue in the United States (US); annually approximately 90,000 valve replacements are conducted in the US. Traditional valve replacement surgery involving the orthotopic replacement of a heart valve is considered an “open heart” surgical procedure. Briefly, the procedure necessitates surgical opening of the thorax, the initiation of extra-corporeal circulation with a heart-lung machine, stopping and opening the heart, excision and replacement of the diseased valve, and re-starting of the heart. While valve replacement surgery typically carries a 1-4% mortality risk in otherwise healthy persons, a significantly higher morbidity is associated to the procedure largely due to the necessity for extra-corporeal circulation. Further, open heart surgery is often poorly tolerated in elderly patients. Thus elimination of the extra-corporeal component of the procedure could result in reduction in morbidities and cost of valve replacement therapies could be significantly reduced.

While replacement of the aortic valve in a transcatheter manner is the subject of intense investigation, lesser attention has been focused on the mitral valve. This is in part reflective of the greater level of complexity associated to the native mitral valve apparatus, and thus, a greater level of difficulty with regards to inserting, anchoring, and retrieving the replacement prosthesis. In particular, repositioning of a collapsible replacement prosthesis and retrieval of a collapsible replacement prosthesis from the native mitral valve present challenges. For example, a prosthetic heart valve may be delivered and secured percutaneously or intravenously using a catheter and endoscope. The disengagement of the anchoring mechanisms and collapsing of the prosthetic heart valve, however, presents a need for more active prosthetic heart valve manipulation within the heart.

Thus, a need exists for delivery devices and methods for transcatheter mitral valve repositioning and/or retrieval.

SUMMARY

Apparatus and methods are described herein for use in the transvascular repositioning and retrieval of a previously-deployed prosthetic mitral valve. In some embodiments, a method for transfemoral retrieval of a prosthetic heart valve implanted within a heart includes inserting a retrieval assembly through the femoral vein and into a heart of a patient until a distal end portion of the retrieval assembly is disposed in the atrium of the heart. The prosthetic heart valve is formed with a shape-memory material. The retrieval assembly includes an outer catheter, a middle catheter, a snare catheter, and a snare member. The snare member is moved distally out of a lumen of the snare catheter and into engagement with an inner frame of the prosthetic heart valve. The retrieval assembly can be manipulated to invert an outer frame of the prosthetic heart valve such that the prosthetic heart valve can be collapsed and retracted into a lumen of the retrieval assembly. In some embodiments, a positioning catheter can be inserted through the apex of the heart to assist in positioning and inverting the prosthetic heart valve.

BRIEF DESCRIPTION OF THE FIGURES

FIGS. 1A and 1B are schematic illustrations of a portion of a prosthetic heart valve, according to an embodiment, shown in a first configuration and a second configuration, respectively.

FIGS. 1C and 1D are schematic illustrations of the portion of the prosthetic heart valve of FIGS. 1A and 1B, respectively, shown disposed within a delivery sheath.

FIGS. 2A and 2B are schematic illustrations of the portion of a prosthetic heart valve of FIGS. 1A and 1B, shown in the first configuration and the second configuration, respectively.

FIGS. 3-5 are front, bottom, and top views of a prosthetic heart valve according to an embodiment.

FIG. 6 is an opened and flattened view of the inner frame of the prosthetic heart valve of FIGS. 3-5, in an unexpanded configuration.

FIGS. 7 and 8 are side and bottom views, respectively, of the inner frame of FIG. 6 in an expanded configuration.

FIG. 9 is an opened and flattened view of the outer frame of the valve of FIGS. 3-5, in an unexpanded configuration.

FIGS. 10 and 11 are side and top views, respectively, of the outer frame of FIG. 9 in an expanded configuration.

FIGS. 12-14 are side, front, and top views of an assembly of the inner frame of FIGS. 6-8 and the outer frame of FIGS. 9-11.

FIG. 15 is a side perspective view of an assembly of an inner frame and an outer frame shown in a biased expanded configuration, according to an embodiment.

FIG. 16 is a side perspective view of the assembly of FIG. 15 with the outer frame shown inverted.

FIG. 17 is side view of the assembly of FIG. 16 shown in a collapsed configuration within a lumen of a delivery sheath.

FIG. 18 is a side view of the assembly of FIG. 17 shown in a first partially deployed configuration.

FIG. 19 is a side view of the assembly of FIG. 17 shown in a second partially deployed configuration.

FIG. 20 is a side view of the assembly of FIG. 17 shown in a third partially deployed configuration in which the inverted outer frame is substantially deployed outside of the delivery sheath.

FIG. 21 is a side view of the assembly of FIG. 17 shown in a fourth partially deployed configuration in which the outer frame has reverted and assumed a biased expanded configuration.

FIGS. 22-24 illustrate steps of a portion of a method to deliver the prosthetic valve of FIGS. 15-21 to an atrium of a heart and within the native mitral annulus.

FIG. 25A is a schematic illustration of a prosthetic mitral valve retrieval system engaged with a prosthetic valve in a first configuration, according to an embodiment.

FIG. 25B is a schematic illustration of the prosthetic mitral valve retrieval system of FIG. 25A with the prosthetic valve in a second configuration in which an inner frame of the prosthetic valve is partially disposed within the retrieval system.

FIG. 25C is a schematic illustration of the prosthetic mitral valve retrieval system of FIG. 25A with the prosthetic valve in a third configuration in which an outer frame of the prosthetic valve is in an inverted configuration.

FIG. 26 is a cross-sectional illustration of a heart with a prosthetic mitral valve retrieval system engaged with a prosthetic mitral valve during a procedure to remove the prosthetic mitral valve from the heart, according to an embodiment.

FIG. 27 is a cross-sectional illustration of the prosthetic mitral valve retrieval system of FIG. 26 during the procedure to remove the prosthetic mitral valve from the heart, with an inner frame of the prosthetic valve disposed partially within the retrieval system.

FIG. 28 is a cross-sectional illustration of the prosthetic mitral valve retrieval system of system of FIG. 26 during the procedure to remove the prosthetic mitral valve from the heart, with an outer frame of the prosthetic mitral valve moved to an inverted configuration relative to the inner frame.

FIG. 29 is a flowchart illustrating a method of retrieving an implanted prosthetic heart valve, according to an embodiment.

DETAILED DESCRIPTION

Apparatus and methods are described herein for retrieval or repositioning of a previously-implanted prosthetic heart valve via a transfemoral approach. Such an approach can be similar to the transfemoral delivery approach for delivering a prosthetic heart valve as described in PCT International Application No. PCT/US2016/012305 (referred to herein as “the '305 PCT Application”) with respect to, for example, FIGS. 43-61, and as described herein, with respect to, for example, FIGS. 22-24.

In some embodiments, a method for transfemoral retrieval of a prosthetic mitral valve includes inserting a retrieval assembly through the femoral vein and septum of a heart of a patient until a distal end portion of the retrieval assembly is disposed in the left atrium of the heart. The prosthetic mitral valve is formed with a shape-memory material. The retrieval assembly includes an outer catheter, a middle catheter, a snare catheter, and a snare member. The snare member is moved distally out of the retrieval assembly into engagement with an inner frame of the prosthetic mitral valve. The retrieval assembly can be manipulated to invert an outer frame of the prosthetic mitral valve such that the prosthetic mitral valve can be collapsed and retracted into a lumen of the retrieval assembly. In some embodiments, a positioning catheter can be inserted through the apex of the heart to assist in positioning and inverting the prosthetic mitral valve.

In some embodiments, an apparatus includes a retrieval system for a prosthetic heart valve previously deployed in a valve annulus. A retrieval assembly of the retrieval system can approach the deployed prosthetic heart valve trans-septally, capture the prosthetic heart valve, dislodge the prosthetic heart valve from the valve annulus, and then either reposition and redeploy the prosthetic heart valve or remove the prosthetic heart valve from the heart. In some embodiments, the repositioning or removal of the previously-deployed prosthetic heart valve can be performed via an outpatient catheterization procedure without requiring major surgery.

FIGS. 1A and 1B are schematic illustrations of a portion of a prosthetic heart valve 100, according to an embodiment, shown in a first configuration and a second configuration respectively, and FIGS. 1C and 1D illustrate the portions of the prosthetic heart valve 100 of FIGS. 1A and 1B, respectively, shown disposed within a lumen of a delivery sheath 126. FIGS. 2A and 2B illustrate a portion of the prosthetic heart valve 100 of FIGS. 1A and 1B, respectively, and show length dimensions for the prosthetic heart valve in each of the first configuration and the second configuration. The prosthetic heart valve 100 (also referred to herein as “prosthetic valve” or “valve”) can be, for example, a prosthetic mitral valve. The valve 100 includes an outer frame 120 and an inner frame 150. The outer frame 120 and the inner frame 150 are each formed as a tubular structure as described in more detail below with reference to FIGS. 3-15. The outer frame 120 and the inner frame 150 can be coupled together at multiple coupling joints 146 disposed about a perimeter of the inner frame 150 and a perimeter of the outer frame 120 as described in more detail below. The valve 100 can also include other features, such as those described with respect to FIGS. 3-15 below. For illustration purposes, only the inner frame 150 and the outer frame 120 are discussed with respect to FIGS. 1A-2B. The various characteristics and features of valve 100 described with respect to FIGS. 1A-2B can apply to any of the prosthetic valves described here.

The outer frame 120 is configured to have a biased expanded or undeformed shape and can be manipulated and/or deformed (e.g., compressed or constrained) and, when released, return to its original (expanded or undeformed) shape. For example, the outer frame 120 can be formed of materials, such as metals or plastics, which have shape memory properties. With regards to metals, Nitinol® has been found to be especially useful since it can be processed to be austenitic, martensitic or super elastic. Other shape memory alloys, such as Cu—Zn—Al—Ni alloys, and Cu—Al—Ni alloys, may also be used. The inner frame 150 can be formed from a laser-cut tube of Nitinol®. The inner frame 150 can also have a biased expanded or undeformed shape and can be manipulated and/or deformed (e.g., compressed and/or constrained) and, when released, return to its original (expanded or undeformed) shape. Further details regarding the inner frame 150 and the outer frame 120 are described below with respect to valve 200 and FIGS. 3-15.

The valve 100 can be delivered and deployed within a left atrium of a heart using a variety of different delivery approaches including, for example, a transfemoral delivery approach, as described in the '305 PCT application, or a transatrial approach, as described in U.S. Provisional Patent Application Ser. No. 62/220,704, entitled “Apparatus and Methods for Transatrial Delivery of Prosthetic Mitral Valve,” or a transjugular approach as described in U.S. Provisional Patent Application Ser. No. 62/305,678 and in U.S. Patent Application Pub. No. 2017/0079790, each incorporated by reference herein. As described above, in some situations, such as when delivering a prosthetic valve to the heart via a transfemoral or transatrial approach, because of the smaller size of the lumen of the delivery sheath, the size of the prosthetic valve during delivery should be sized accordingly. Thus, it is desirable to have a prosthetic valve that can be reconfigured between a biased expanded configuration for implantation in the heart (e.g., within a native mitral annulus) and a delivery configuration that has a smaller outer perimeter or profile to allow for delivery within the lumen of the delivery sheath. The prosthetic valve 100 and the embodiments of a prosthetic valve described herein can be constructed and formed to achieve these desired functions and characteristics.

More specifically, the valve 100 can have a biased expanded configuration (as shown in FIGS. 1A and 2A), an inverted configuration (as shown in FIGS. 1B and 2B), and a compressed or collapsed configuration (as shown in FIGS. 1C and 1D). The expanded configuration allows the valve 100 to function when implanted within the heart. The valve 100 can be moved to the inverted configuration and the compressed or collapsed configuration for delivery of the valve 100 to the heart of a patient.

To enable the valve 100 to be moved to the inverted configuration, the outer frame 120 can be coupled to the inner frame 150 in such a manner to allow the outer frame 120 to move relative to the inner frame 150. More specifically, the coupling joints 146 can couple the outer frame 120 to the inner frame 150 in such a manner to allow the outer frame 120 to be moved relative to the inner frame 150. For example, in some embodiments, the coupling joints 146 can be configured to allow the outer frame 120 to rotate about the coupling joint 146 relative to the inner frame 150. In some embodiments, coupling joints can provide a pivotal coupling between the outer frame 120 and the inner frame 150. In some embodiments, the coupling joints can provide a flexible attachment between the outer frame 120 and the inner frame 150. The coupling joints 146 can be a variety of different types and configurations as described herein with reference to the various embodiments of a prosthetic valve. For example, the coupling joints 146 can include a living hinge, a flexible member, sutures, a suture wrapped through an opening, a pin or tab inserted through an opening, or any combinations thereof.

To move the valve 100 from the expanded configuration (FIG. 1A) to the inverted configuration (FIG. 1B), the outer frame 120 is moved to a prolapsed or inverted configuration relative to the inner frame 150, as shown in FIGS. 1B, 1D and 2B, by moving (e.g., rotating, pivoting, flexing) the outer frame 120 about the coupling joints 146. The elastic or superelastic structure of outer frame 120 of valve 100 also allows the outer frame 120 to be moved to, and disposed in, the prolapsed or inverted configuration relative to the inner frame 150. To move the outer frame 120 to the inverted configuration relative to the inner frame 150, the outer frame 120 is folded or inverted distally (to the right in FIG. 1B) relative to the inner frame 150 via the coupling joints 146. As shown in FIGS. 1A and 2A, the outer frame 120 is in a first position relative to the inner frame 150 prior to being inverted in which an open or free end portion 116 (also referred to as the atrium portion 116 of the outer frame 120) is disposed proximally or to the left of the coupling joints 146 and in the same direction as a free end portion 147 (also referred to as a second end portion of the inner frame) of the inner frame 150. When the outer frame 120 is moved to an inverted configuration (i.e., second position relative to the inner frame 150), the free end portion 116 is disposed distally of the coupling joints 146 (or to the right in FIGS. 1B and 2B) and in an opposite direction as the free end portion 147 of the inner frame 150. Said another way, when the valve 100 is in a biased expanded configuration (e.g., FIG. 1A), the coupling joints 146 are disposed between a first end portion 144 (also referred to as a tether coupling portion) of the inner frame 150 and the free end portion 116 of the outer frame 120. When the valve 100 is in the inverted configuration (e.g., FIG. 1B) (i.e., the outer frame 120 has been moved to an inverted configuration or position), the coupling joints 146 are disposed between the free end portion or second end portion 147 of the inner frame 150 and the free end portion 116 of the outer frame 120.

When in the inverted configuration, an overall length of the valve 100 is increased, but a length of the inner frame 150 and a length of the outer frame 120 remains the same (or substantially the same). For example, as shown in FIGS. 2A and 2B an overall length L1 of the valve 100 in the biased expanded configuration (prior to being inverted as shown in FIG. 2A) is less than the overall length L2 of the valve 100 when in the inverted configuration (FIG. 2B). A length Li of the inner frame 150 and a length Lo of the outer frame 120 is substantially the same (or the same) when the valve 100 is in both the biased expanded configuration and the inverted configuration. In addition, in some instances, depending on the specific configuration of the outer frame, an overall outer perimeter or outer diameter of the valve 100 can be smaller when the valve 100 is in the inverted configuration.

With the valve 100 in the inverted configuration, the valve 100 can be placed within a lumen of the delivery sheath 126 for delivery of the valve 100 to the left atrium of the heart, as shown in FIG. 1D. When placed within the lumen of the delivery sheath 126, the valve 100 is moved to the collapsed or compressed configuration in which the outer diameter or outer perimeter of the valve 100 is reduced. Because the valve 100 is in the inverted configuration, the valve 100 is able to be placed within a smaller delivery sheath 126 than would otherwise be possible. For example, for comparison purposes, FIG. 1C illustrates the valve 100 placed within a lumen of a delivery sheath 126′ where the valve 100 has not been moved to an inverted configuration prior to being disposed within the delivery sheath 126′. As shown in FIG. 1C, an outer diameter of the valve 100 is reduced, but not to as small of a diameter as for the valve 100 when placed in a delivery sheath 126 when in the inverted configuration. Thus, in FIG. 1C, the valve 100 has an overall outer perimeter or outer diameter D1 and in FIG. 1D, the valve 100 has an overall outer perimeter or outer diameter D2, which is less than D1.

Thus, by disposing the outer frame 120 in the inverted configuration, the valve 100 can be collapsed into a smaller overall diameter, i.e. placed in a smaller diameter delivery sheath 126, than would be possible if the valve 100 were merely collapsed radially. This is because when the valve is in the biased expanded configuration, the inner frame 150 is nested within an interior of the outer frame 120, and thus the outer frame 120 must be collapsed around the inner frame 150. In some embodiments, the inner frame 150 and the outer frame 120 are disposed concentrically. Whereas in the inverted configuration, the inner frame 150 and the outer frame 120 are arranged axially with respect to each other (i.e., the inner frame is not nested within the outer frame 150), such that the outer frame 120 can be collapsed without needing to accommodate all of the structure of the inner frame 150 inside it. In other words, with the inner frame 150 disposed mostly inside or nested within the outer frame 120, the layers or bulk of the frame structures cannot be compressed to as small a diameter. In addition, if the frames are nested, the structure is less flexible, and therefore, more force is needed to bend the valve, e.g. to pass through tortuous vasculature or to make tight turn in the left atrium after passing through the atrial septum to be properly oriented for insertion into the mitral valve annulus.

FIGS. 3-14 illustrate another embodiment of a prosthetic heart valve that can be delivered and deployed within a left atrium of a heart using a variety of different delivery approaches including, for example, a transfemoral delivery approach, a transatrial delivery approach, or a transjugular approach. FIGS. 3-5 are front, bottom, and top views, respectively, of a prosthetic heart valve 200 according to an embodiment. Prosthetic heart valve 200 (also referred to herein as “valve” or “prosthetic valve”) is designed to replace a damaged or diseased native heart valve such as a mitral valve. Valve 200 includes an outer frame assembly 210 and an inner valve assembly 240 coupled to the outer frame assembly 210.

As shown, outer frame assembly 210 includes an outer frame 220, covered on all or a portion of its outer face with an outer covering 230, and covered on all or a portion of its inner face by an inner covering 232. Outer frame 220 can provide several functions for prosthetic heart valve 200, including serving as the primary structure, as an anchoring mechanism and/or an attachment point for a separate anchoring mechanism to anchor the valve to the native heart valve apparatus, a support to carry inner valve assembly 240, and/or a seal to inhibit paravalvular leakage between prosthetic heart valve 200 and the native heart valve apparatus.

Outer frame 220 has a biased expanded configuration and can be manipulated and/or deformed (e.g., compressed and/or constrained) and, when released, return to its original unconstrained shape. To achieve this, outer frame 220 can be formed of materials, such as metals or plastics, which have shape memory properties. With regards to metals, Nitinol® has been found to be especially useful since it can be processed to be austenitic, martensitic or super elastic. Other shape memory alloys, such as Cu—Zn—Al—Ni alloys, and Cu—Al—Ni alloys, may also be used.

As best shown in FIG. 3, outer frame assembly 210 has an upper end (e.g., at the atrium portion 216), a lower end (e.g., at the ventricle portion 212), and a medial portion (e.g., at the annulus portion 214) therebetween. The upper end or atrium portion 216 (also referred to as “outer free end portion”) defines an open end portion of the outer frame assembly 210. The medial or annulus portion 214 of the outer frame assembly 210 has a perimeter that is configured (e.g., sized, shaped) to fit into an annulus of a native atrioventricular valve. The upper end of the outer frame assembly 210 has a perimeter that is larger than the perimeter of the medial portion. In some embodiments, the perimeter of the upper end of the outer frame assembly 210 has a perimeter that is substantially larger than the perimeter of the medial portion. As shown best in FIG. 5, the upper end and the medial portion of the outer frame assembly 210 has a D-shaped cross-section. In this manner, the outer frame assembly 210 promotes a suitable fit into the annulus of the native atrioventricular valve.

Inner valve assembly 240 includes an inner frame 250, an outer covering (not shown), and leaflets 270. As shown, the inner valve assembly 240 includes an upper portion having a periphery formed with multiple arches. The inner frame 250 includes six axial posts or frame members that support the outer covering and leaflets 270. Leaflets 270 are attached along three of the posts, shown as commissure posts 252 (best illustrated in FIG. 4), and the outer covering is attached to the other three posts, 254 (best illustrated in FIG. 4), and optionally to commissure posts 252. Each of the outer covering and leaflets 270 are formed of approximately rectangular sheets of material, which are joined together at their upper, or atrium end. The lower, ventricle end of outer covering may be joined to inner covering 232 of outer frame assembly 210, and the lower, ventricle end of leaflets 270 may form free edges 275, though coupled to the lower ends of commissure posts 252.

Although inner valve assembly 240 is shown as having three leaflets, in other embodiments, an inner valve assembly can include any suitable number of leaflets. The leaflets 270 are movable between an open configuration and a closed configuration in which the leaflets 270 coapt, or meet in a sealing abutment.

Outer covering 230 of the outer frame assembly 210 and inner covering 232 of outer frame assembly 210, outer covering of the inner valve assembly 240 and leaflets 270 of the inner valve assembly 240 may be formed of any suitable material, or combination of materials, such as those discussed above. In this embodiment, the inner covering 232 of the outer frame assembly 210, the outer covering of the inner valve assembly 240, and the leaflets 270 of the inner valve assembly 240 are formed, at least in part, of porcine pericardium. Moreover, in this embodiment, the outer covering 230 of the outer frame assembly 210 is formed, at least in part, of polyester.

Inner frame 250 is shown in more detail in FIGS. 6-8. Specifically, FIGS. 6-8 show inner frame 250 in an undeformed, initial state (FIG. 6), a side view of the inner frame 250 in an expanded configuration (FIG. 7), and a bottom view of the inner frame 250 in the expanded configuration (FIG. 8), respectively, according to an embodiment.

In this embodiment, inner frame 250 is formed from a laser-cut tube of Nitinol®. Inner frame 250 is illustrated in FIG. 6 in an undeformed, initial state, i.e. as laser-cut, but cut and unrolled into a flat sheet for ease of illustration. Inner frame 250 can be divided into four portions, corresponding to functionally different portions of the inner frame 250 in final form: atrial portion 247, body portion 242, strut portion 243, and tether clamp or connecting portion 244. Strut portion 243 includes six struts, such as strut 243A, which connect body portion 242 to tether connecting portion 244.

Tether connecting portion 244 (also referred to as first end portion of inner frame) includes longitudinal extensions of the struts, connected circumferentially by pairs of opposed, slightly V-shaped connecting members (or “micro-Vs”). Tether connecting portion 244 is configured to be radially collapsed by application of a compressive force, which causes the micro-Vs to become more deeply V-shaped, with the vertices moving closer together longitudinally and the open ends of the V shapes moving closer together circumferentially. Thus, tether connecting portion 244 can be configured to compressively clamp or grip one end of a tether, either connecting directly onto a tether line (e.g. braided filament line) or onto an intermediate structure, such as a polymer or metal piece that is in turn firmly fixed to the tether line.

In contrast to tether connecting portion 244, atrial portion 247 (also referred to as “inner frame free end portion”) and body portion 242 are configured to be expanded radially. Strut portion 243 forms a longitudinal connection and radial transition between the expanded body portion and the compressed tether connecting portion 244. Body portion 242 provides an inner frame coupling portion 245 that includes six longitudinal posts, such as post 242A. The inner frame coupling portion 245 can be used to attach leaflets 270 to inner frame 240, and/or can be used to attach inner assembly 240 to outer assembly 210, such as by connecting inner frame 250 to outer frame 220. In the illustrated embodiment, the posts include openings through which connecting members (such as suture filaments and/or wires) can be passed to couple the posts to other structures.

Inner frame 250 is shown in a fully deformed, i.e. the final, deployed configuration, in side view and bottom view in FIGS. 7 and 8, respectively.

Outer frame 220 of valve 200 is shown in more detail in FIGS. 9-11. In this embodiment, outer frame 220 is also formed from a laser-cut tube of Nitinol®. Outer frame 220 is illustrated in FIG. 9 in an undeformed, initial state, e.g., as laser-cut, but cut and unrolled into a flat sheet for ease of illustration. Outer frame 220 can be divided into an outer frame coupling portion 271, a body portion 272, and a cuff portion 273 (which includes the atrium or free end portion 216), as shown in FIG. 9. Outer frame coupling portion 271 includes multiple openings or apertures, such as 271A, by which outer frame 220 can be coupled to inner frame 250, as discussed in more detail below.

Outer frame 220 is shown in a fully deformed, e.g., the final, deployed configuration, in side view and top view in FIGS. 10 and 11, respectively. As best seen in FIG. 11, the lower end of outer frame coupling portion 271 forms a roughly circular opening (identified by “0” in FIG. 11). The diameter of this opening preferably corresponds approximately to the diameter of body portion 242 of inner frame 250, to facilitate coupling of the two components of valve 200.

Outer frame 220 and inner frame 250 are shown coupled together in FIGS. 12-14, in front, side, and top views, respectively. The two frames collectively form a structural support for a prosthetic valve such as valve 200. The frames support the valve leaflet structure (e.g., leaflets 270) in the desired relationship to the native valve annulus, support the coverings (e.g., outer covering 230, inner covering 232, outer covering of the inner valve assembly 240) for the two frames to provide a barrier to blood leakage between the atrium and ventricle, and couple to the tether (e.g., tether assembly 290) (by the inner frame 250) to aid in holding the prosthetic valve 200 in place in the native valve annulus by the tether connection to the ventricle wall. The outer frame 220 and the inner frame 250 are connected at six coupling points (representative points are identified as “C”). In this embodiment, the coupling points are implemented with a mechanical fastener, such as a short length of wire, passed through an aperture (such as aperture 271A) in outer frame coupling portion 271 and corresponding openings in inner frame coupling portion 245 (e.g., longitudinal posts, such as post 242A) in body portion 242 of inner frame 250. Inner frame 250 is thus disposed within the outer frame 220 and securely coupled to it.

FIGS. 15-21 illustrate a method of reconfiguring a prosthetic heart valve 300 (e.g., prosthetic mitral valve) prior to inserting the prosthetic heart valve 300 into a delivery sheath 326 (see, e.g., FIGS. 17-21) for delivery into the atrium of the heart. The prosthetic heart valve 300 (also referred to herein as “valve”) can be constructed the same as or similar to, and function the same as or similar to the valves 100 and 200 described above. Thus, some details regarding the valve 300 are not described below. It should be understood that for features and functions not specifically discussed, those features and functions can be the same as or similar to the valve 200.

As shown in FIG. 15, the valve 300 has an outer frame 320 and an inner frame 350. As discussed above for valves 100 and 200, the outer frame 320 and the inner frame 350 of valve 300 can each be formed with a shape-memory material and have a biased expanded configuration. The outer frame 320 and the inner frame 350 can be moved to a collapsed configuration for delivery of the valve 300 to the heart. In this example method of preparing the valve 300 for delivery to the heart, the outer frame 320 of the valve 300 is first disposed in a prolapsed or inverted configuration as shown in FIG. 16. Specifically, the elastic or superelastic structure of outer frame 320 of valve 300 allows the outer frame 320 to be disposed in the prolapsed or inverted configuration prior to the valve 300 being inserted into the lumen of the delivery sheath 326. As shown in FIG. 16, to dispose the outer frame 320 in the inverted configuration, the outer frame 320 is folded or inverted distally (to the right in FIG. 16) such that an open free end 316 of the outer frame 320 is pointed away from an open free end 347 of the inner frame 350. As described above for valve 100, in this inverted configuration, the overall outer perimeter or outer diameter of the valve 300 is reduced and the overall length is increased. For example, the diameter D1 shown in FIG. 15 is greater than the diameter D2 shown in FIG. 16, and the length L1 (shown in FIG. 12 for valve 200) is less than the length L2 shown in FIG. 16 for valve 300. With the outer frame 320 in the inverted configuration relative to the inner frame 350, the valve 300 can be placed within a lumen of a delivery sheath 326 as shown in FIG. 17 for delivery of the valve 300 to the left atrium of the heart. By disposing the outer frame 320 in the inverted configuration relative to the inner frame 350, the valve 300 can be collapsed into a smaller overall diameter, i.e. when placed in a smaller diameter delivery sheath, than would be possible if the valve 300 in the configuration shown in FIG. 15 were collapsed radially without being inverted. This is because in the configuration shown in FIG. 15, the two frames are concentric or nested, and thus the outer frame 320 must be collapsed around the inner frame 350, whereas in the configuration shown in FIG. 16, the two frames are substantially coaxial but not concentric or nested. Thus, in the configuration shown in FIG. 16, the outer frame 320 can be collapsed without the need to accommodate the inner frame 350 inside of it. In other words, with the inner frame 350 disposed mostly inside or nested within the outer frame 320, the layers or bulk of the frame structures cannot be compressed to as small a diameter. In addition, if the frames are nested, the structure is less flexible, and therefore, more force is needed to bend the valve, e.g. to pass through tortuous vasculature or to make tight turn in the left atrium after passing through the atrial septum to be properly oriented for insertion into the mitral valve annulus.

FIGS. 22-24 illustrate a portion of a procedure to deliver the valve 300 to the heart. In this embodiment, the valve 300 is shown being delivered via a transfemoral delivery approach as described, for example, in the '305 PCT application incorporated by reference above. The delivery sheath 326, with the valve 300 disposed within a lumen of the delivery sheath 326 and in an inverted configuration as shown in FIG. 17, can be inserted into a femoral puncture, through the femoral vein, through the inferior vena cava, into the right atrium, through the septum Sp and into the left atrium LA of the heart. With the distal end portion of the delivery sheath 326 disposed within the left atrium of the heart, the valve 300 can be deployed outside a distal end of the delivery sheath 326. For example, in some embodiments, a pusher device 338 (shown in FIG. 23) can be used to move or push the valve 300 out the distal end of the delivery sheath 326. As shown in FIGS. 22-24, a tether 336 can be attached to the valve 300, and extend though the mitral annulus, through the left ventricle LV, and out a puncture site at the apex Ap. In some embodiments, the valve 300 can be moved out of the delivery sheath 326 by pulling proximally on the tether 336. In some embodiments, the valve 300 can be deployed by pushing with the pusher device and pulling with the tether.

As the valve 300 exits the lumen of the delivery sheath 326, the outer frame assembly 310 exits first in its inverted configuration as shown in the progression of FIGS. 18-20 (see also FIG. 22). After the outer frame assembly 310 is fully outside of the lumen of the delivery sheath 326, the outer frame 320 can revert to its expanded or deployed configuration as shown in FIGS. 21, 23 and 24. In some embodiments, the outer frame 320 can revert automatically after fully exiting the lumen of the delivery sheath due to its shape-memory properties. In some embodiments, a component of the delivery sheath or another device can be used to aid in the reversion of the outer frame assembly 310. In some embodiments, the pusher device 338 and/or the tether 336 can be used to aid in the reversion of the outer frame assembly 310. The valve 300 can continue to be deployed until the inner frame 350 is fully deployed with the left atrium and the valve 300 is in the expanded or deployed configuration (as shown, e.g., in FIGS. 15 and 24). The valve 300 and the tether 336 can then be secured to the apex of the heart with an epicardial pad device 339 as shown in FIG. 24 and as described in more detail in the '305 PCT application.

FIGS. 25A-25C are schematic illustrations of a retrieval system 405 during various stages of a procedure to engage, capture, and remove a prosthetic heart valve after it has been deployed within a heart (not shown in FIGS. 25A-25C). As shown in FIG. 25A, the retrieval system 405 can include a retrieval assembly 402. The retrieval assembly 402 can include an outer catheter 403, a middle catheter 404, a snare catheter 406, and a snare member 415. The snare member 415 can be movably disposed within a lumen of the snare catheter 406 and the snare catheter 406 can be movably disposed within a lumen of the middle catheter 404. Similarly, the middle catheter 404 can be movably disposed within a lumen of the outer catheter 403. The outer catheter 403 can have a rigid distal tip. Optionally, in some embodiments, the retrieval system 405 can also include an apical positioning catheter 419.

The retrieval system 405 can engage with a valve assembly (e.g., a prosthetic heart valve) such that the retrieval system 405 can be used to control the position and configuration of the valve assembly. In particular, as shown in FIG. 25A, the retrieval system 405 can engage with and retrieve a previously-implanted valve assembly 401 from, for example, a mitral annulus. The valve assembly 401 can include a valve 400 and a tether 436. The valve 400 and the tether 436 can be constructed the same as or similar to, and function the same as or similar to, any of the valves and tethers described herein and in the '305 PCT Application incorporated by reference above. For example, the valve 400 can include an inner frame 440 and an outer frame 410. Additionally, in some embodiments, the inner frame 440 can include a body portion and a tether connecting portion. The tether 436 can be coupled to the inner frame 440 via the tether connecting portion. A strut portion of the inner frame 440 can connect the tether connecting portion to the body portion. The outer frame 410 and the inner frame 440 can be formed with a shape-memory material. As a result, the outer frame 410 can be movably coupled to the inner frame 440 such that the valve 400 can be moved between a biased expanded or deployed configuration, an inverted configuration, and a collapsed or compressed configuration. The expanded configuration allows the valve assembly 401 to function when implanted within the heart. The valve 400 can be moved to the inverted configuration and/or the compressed or collapsed configuration for delivery of the valve assembly 401 to, or retrieval of the valve assembly 401 from, the heart of a patient.

More specifically, for delivery of the valve assembly 401 to the heart via a delivery sheath and/or retrieval of the valve assembly 401 from the heart via the retrieval assembly 402, the outer frame 410 can be moved to a prolapsed or inverted configuration relative to the inner frame 440 by folding or distally inverting the outer frame 410 via, for example, coupling joints. Prior to being inverted, the outer frame 410 can be in a first position relative to the inner frame 440 in which an open or free end portion is disposed in the same direction as a free end portion of the inner frame 440, as shown in FIG. 25A. When the outer frame 410 is moved to an inverted configuration, the free end portion of the outer frame 410 is disposed in an opposite direction as the free end portion of the inner frame 440, as shown in FIG. 25C.

When in the inverted configuration, an overall length of the valve 400 is increased, but a length of the inner frame 440 and a length of the outer frame 410 remain the same (or substantially the same). In addition, in some instances, depending on the specific configuration of the outer frame 410, an overall outer perimeter or outer diameter of the valve 400 can be smaller when the valve 400 is in the inverted configuration. For example, with the valve 400 in the inverted configuration, the valve 400 can be placed within a lumen of a delivery sheath or the retrieval assembly 402 for delivery to or retrieval from, respectively, the left atrium of the heart. Before inserting the valve 400 into a lumen of the delivery sheath or the retrieval assembly 402, the valve 400 can first be moved to the inverted configuration and then to a collapsed or compressed configuration within the lumen of the delivery sheath or retrieval assembly 402 in which the outer diameter or outer perimeter of the valve 400 is reduced. Because the valve 400 is in the inverted configuration, the valve 400 can be placed within a smaller delivery sheath or retrieval assembly 402 than would be possible if the valve 400 were merely collapsed radially. This is because when the valve 400 is in the biased expanded configuration, the inner frame 440 is nested within an interior of the outer frame 410, and thus the outer frame 410 must be collapsed around the inner frame 440 if merely collapsed radially. Whereas, in the inverted configuration, the inner frame 440 and the outer frame 410 are arranged axially with respect to each other (i.e., the inner frame is not nested within the outer frame 410), such that the outer frame 410 can be collapsed without needing to accommodate all of the structure of the inner frame 440 inside the outer frame 410. In other words, with the inner frame 440 disposed mostly inside or nested within the outer frame 410, the layers or bulk of the frame structures cannot be compressed to as small a diameter. In addition, the valve 400 is more flexible in the inverted configuration. In other words, less force is required to bend the valve 400 for the valve 400 to pass through tortuous vasculature or to make a tight turn (e.g., into the left atrium after passing through the atrial septum to be properly oriented for insertion into the mitral valve annulus or, for retrieval, out of the mitral valve annulus to be properly oriented to pass through the atrial septum). Conversely, if the outer frame 410 and the inner frame 440 are nested, the valve 400 is less flexible and more force is needed to bend the valve 400.

The snare member 415 can be any suitable shape and can include an engagement portion 417. The engagement portion 417 can be extendable from an undeployed configuration (not shown) when disposed within the lumen of the snare catheter 419 to a deployed configuration when disposed outside of the snare catheter 419, as shown in FIG. 25A. In some embodiments, the undeployed configuration of the engagement portion 417 can be a collapsed configuration where the engagement portion 417 is bent, squeezed, or otherwise reduced in diameter to fit into the lumen of the snare catheter 419. The engagement portion 417 can be formed with a shape-memory material and have a biased expanded or deployed configuration such that the engagement portion 417 automatically expands as it is moved out of the lumen of the snare catheter 419.

The engagement portion 417 of the snare member 415 is shaped and sized such that, in the expanded or deployed configuration, the engagement portion 417 can surround and engage with a portion of the inner frame 440 of the valve 400. As shown in FIG. 25A, as the engagement portion 417 is pushed or moved outside the distal end of the snare catheter 406, the engagement portion 417 can transition to the expanded configuration. In the expanded configuration, the engagement portion 417 can be positioned relative to the inner frame 440 of the valve 400 such that the snare member 415 engages with the inner frame 440. For example, the engagement portion 417 can be positioned such that the engagement portion 417 surrounds the inner frame 440. When the engagement portion 417 is positioned around the inner frame 440, the engagement portion 417 can be manipulated such that the engagement portion 417 grasps the inner frame 440 (e.g., the engagement portion 417 can be reduced in diameter to securely engage with the inner frame 440). When the engagement portion 417 is securely engaged with the inner frame 440, the engagement portion 417 can be further manipulated to control the position of the inner frame 440. Additionally, the engagement portion 417 can apply a compressive force to partially collapse the inner frame 440, reducing the outer diameter of the inner frame 440 such that the inner frame 440 can be retracted into the middle catheter 404 and/or the outer catheter 403 via proximal movement of the snare member 415 as shown in FIG. 25B.

In some embodiments, as shown in FIGS. 25A-25C, the engagement portion 417 of the snare member 415 can be formed as a loop or lariat. In such embodiments, the engagement portion 417 can have a biased expanded configuration such that the engagement portion 417 automatically transitions to a loop configuration upon being pushed or otherwise moved out of the distal end of the snare catheter 406. The engagement portion 417 can be reduced in diameter to capture and/or compress a portion of the valve 400. For example, the snare member 415 can be disposed within a lumen of a pusher tube (not shown). The pusher tube can be translated distally along the snare member 415 to reduce the diameter of the engagement portion 417 such that the engagement portion 417 applies an engagement and/or compressive force on the inner frame 440.

Although the snare member 415 is shown in FIGS. 25A-25C as including a single loop or lariat, in other embodiments, the engagement portion 417 or, alternatively, the entire snare member 415 can be shaped as a coil and sized such that, in the expanded or deployed configuration, the engagement portion 417 can surround the inner frame 440 and engage with the inner frame 440. In such an embodiment, the engagement portion 417 can be formed with a shape-memory material and the coil shape can be elongated in a delivery configuration inside the snare catheter 406. The coil shape can include multiple loops having the same or different diameters when expanded. As the engagement portion 417 is pushed outside the distal end of the snare catheter 406, the portion of the engagement portion 417 outside of the distal end of the snare catheter 406 can transition to an expanded coil configuration. For example, in some embodiments, as a length of the engagement portion 417 is pushed outside of the distal end of the snare catheter 406, the diameter of the engagement portion 417 can enlarge such that the inner frame 440 can be received within the coil shape formed by the engagement portion 417. When the engagement portion 417 is a sufficient size to receive the inner frame 440, the coil can be moved further distally to surround the inner frame 440. Then, the snare catheter 406 can be moved distally relative to the snare member 415 such that the engagement portion 417 is partially withdrawn into a lumen of the snare member 415. As a result, the diameter of the engagement portion 417 can decrease, causing the engagement portion 417 to engage with and apply a compressive force to the inner frame 440. Thus, the snare member 415 can be used to control the position and/or diameter of the inner frame 440.

As described above and as shown in FIG. 25B, the inner frame 440 of the valve 400 can be retracted into the middle catheter 404 and/or the outer catheter 403 via a proximal movement of the snare member 415, while the engagement portion 417 applies a compressive force to the inner frame 440. The snare member 415 can be pulled further proximally such that the outer frame 410 is pulled into abutting contact with the rigid distal tip of the distal end of the outer catheter 403. As the snare member 415 pulls the inner frame 440 further proximally relative to the outer catheter 403, the outer frame 410 can be moved (i.e., flipped) into the inverted configuration as a result of the force applied by the rigid distal tip of the outer catheter 403 against the outer frame 410, as shown in FIG. 25C. The snare member 415 can continue to be retracted until the outer frame 410 is fully within the outer catheter 403.

In some embodiments, the apical positioning catheter 419 (also referred to herein as “the positioning catheter 419”) can be used to position and/or orient the valve assembly 401 for repositioning and/or retrieval of the valve assembly 401. The positioning catheter 419 can be inserted through the apex of the heart and translated along the tether 436 (i.e., the tether 436 can be threaded through a lumen of the positioning catheter 419). The positioning catheter 419 can be pushed into abutting contact with the valve 400 such that a portion of the valve 400 is disposed within a lumen of the positioning catheter 419. The positioning catheter 419 can then be used to help move the valve 400 toward the retrieval assembly 402 or reposition the valve 400. In some embodiments, the positioning catheter 419 can engage with the valve 400 such that the positioning catheter 419 can control the movement of the valve 400 in some or all directions (e.g., distal, proximal, rotational, and/or lateral movement). For example, in some embodiments, the positioning catheter 419 can be moved towards the valve 400 along the tether 436 while the tether 436 is simultaneously pulled taut away from the valve 400 such that the valve 400 is positioned in abutting contact with the distal end of the positioning catheter 419. With the tether 436 continuing to be held taut, the positioning catheter 419 can then be used to control the position of the valve 400. In some embodiments, the positioning catheter 419 can be used to aid in transitioning the outer frame 410 between the unbiased, expanded configuration and the inverted configuration. For example, in some embodiments, the positioning catheter 419 can be pushed towards the valve 400 along the tether 436 while the tether 436 is simultaneously pulled taut away from the valve 400 such that the distal end of the positioning catheter 419 can compress or partially collapse a portion of the valve 400, such as, for example, the strut portion. The positioning catheter 419 can then assist in pushing the valve 400 toward and/or into the retrieval assembly 402, assisting in providing the force required to transition the valve 400 to the inverted configuration.

In use, the valve assembly 401 can be delivered to a heart as described above (e.g., with respect to FIGS. 22-24) and as described in the '305 PCT Application. For example, the valve assembly 401 can be placed in the distal end of a delivery sheath in the inverted configuration and the delivery sheath can be introduced through a femoral vein puncture and extended through the femoral vein, through the inferior vena cava, into the right atrium, through a trans-septal puncture of the septum of the heart, and into the left atrium or left ventricle of the heart. With the distal end portion of the delivery sheath disposed within the left atrium or left ventricle of the heart, the valve 400 can be deployed outside a distal end of the delivery sheath. For example, in some embodiments, a pusher device can be used to move or push the valve 400 out of the distal end of the delivery sheath. In some embodiments, the tether 436 can extend through the mitral annulus, through the left ventricle, and out of a puncture site at the apex of the heart. In such embodiments, the valve 400 can be moved out of the delivery sheath by pulling proximally on the tether 436. In some embodiments, the valve 400 can be deployed by pushing with the pusher device and pulling the tether 436. As the valve 400 exits the lumen of the delivery sheath, the outer frame 410 exits first in the inverted configuration. After the outer frame 410 is fully outside of the lumen of the delivery sheath, the outer frame 410 can revert to its expanded or deployed configuration. In some embodiments, the outer frame 410 can revert automatically after fully exiting the lumen of the delivery sheath due to its shape-memory properties. In some embodiments, a component of the delivery sheath or another device can be used to aid in the reversion of the outer frame 410. In some embodiments, the pusher device and/or the tether 436 can be used to aid in reversion of the outer frame 410. The valve 400 can continue to be deployed until the inner frame 440 is fully deployed within the left atrium and the valve 400 is in the expanded or deployed configuration. The valve 400 can then be securely implanted in the mitral annulus. Additionally, the tether 436 of the valve assembly 401 can then be secured to the apex of the heart with an epicardial pad device, similarly as shown and described with reference to FIG. 24 above. The delivery sheath and any other delivery instruments can then be removed.

With the valve assembly 401 in the deployed configuration within the mitral annulus, the retrieval system 405 can be used to reposition and/or retrieve the valve assembly 401. In some embodiments, the retrieval assembly 402 can approach the left atrium of the heart transfemorally along the transfemoral trans-septal route (i.e., the same path described above for the delivery of the valve assembly 401). In other words, the outer catheter 403, middle catheter 404, and snare catheter 406 of the retrieval assembly 402 can be introduced through a femoral vein puncture and extended through the femoral vein, through the inferior vena cava, into the right atrium, through a trans-septal puncture of the septum of the heart, and into the left atrium of the heart. In other embodiments, the retrieval assembly 402 can approach the valve assembly 401 transatrially, transjugularly, or along any other suitable path. Additionally, in embodiments in which the tether 436 has been secured to the apex of the heart via an epicardial pad device, the tether 436 can be separated from the epicardial pad device through any suitable means.

As described above, the valve 400 can be transitioned to the inverted configuration before being moved into the retrieval assembly 402 so that the valve 400 can fit within a smaller diameter retrieval assembly 402 and so that the retrieval assembly 402 and valve 400 can bend more easily when being maneuvered through the body. To transition the valve 400 to the inverted configuration, once the distal end of the retrieval assembly 402 is within the left atrium of the heart, the snare member 415 can be extended outside of the distal end of the snare catheter 406. As the snare member 415 is pushed out of the distal end of the snare catheter 406, the engagement portion 417 of the snare member 415 can transition from the undeployed configuration to the deployed configuration. With the engagement portion 417 in the deployed configuration, the snare member 415 can be moved toward the valve 400 such that the engagement portion 417 surrounds the inner frame 440, as shown in FIG. 25A. The engagement portion 417 can then be manipulated such that the engagement portion 417 grasps the inner frame 440 (e.g., the engagement portion 417 can be reduced in diameter to securely engage with the inner frame 440). When the engagement portion 417 is securely engaged with the inner frame 440, the engagement portion 417 can be further manipulated to apply a compressive force to reduce the diameter of the inner frame 440 to a diameter sufficiently small to fit within the middle catheter 404.

While compressing the inner frame 440, the snare member 415 can be retracted proximally relative to the snare catheter 406 and/or the snare catheter 406 can be retracted proximally relative to the middle catheter 404. As a result, at least a portion of the inner frame 440 can be pulled into a lumen of the middle catheter 404, as shown in FIG. 25B. The snare member 415, snare catheter 406, and middle catheter 404 can then be pulled proximally relative to the outer catheter 403 such that the outer frame 410 transitions to the inverted configuration. More specifically, the proximal movement of the inner frame 440 can cause the outer frame 410 to be pulled against the rigid tip of the distal end of the outer catheter 403 as shown in FIG. 25B. As the inner frame 440 is pulled further proximally, the rigid tip of the outer catheter 403 can force the outer frame 410 to flip into the inverted configuration, as shown in FIG. 25C. The snare member 415, snare catheter 406, and middle catheter 404 can then continue to be retracted until the outer frame 410 is fully within the outer catheter 403.

Optionally, the positioning catheter 419 can be used to aid in positioning and orienting the valve assembly 401 for repositioning and/or retrieval. In such embodiments, as shown in FIG. 25C, the positioning catheter 419 can be inserted through the apex of the heart (not shown) and translated along the tether 436. With the tether 436 pulled taut through the positioning catheter 419, the positioning catheter 419 can be moved into abutting contact with the valve 400 such that the positioning catheter 419 can be used to help move the valve 400 toward and/or into the retrieval assembly 402. Additionally, in some embodiments, the positioning catheter 419 can be used to aid in transitioning the outer frame 410 between the expanded or deployed configuration and the inverted configuration. For example, as shown in FIGS. 25B and 25C, the positioning catheter 419 can push the inner frame 440 and/or a central portion of the outer frame 410 into the outer catheter 403 to assist the outer frame 410 in transitioning (i.e., flipping) to the inverted position. Additionally, in some embodiments, the positioning catheter 419 can be pushed towards the valve 400 such that the positioning catheter 419 compresses or partially collapses a portion of the valve 400, such as, for example, the strut portion. The positioning catheter 419 can then assist in pushing the valve 400 toward and/or into the retrieval assembly 402 by assisting in providing the force required to transition the valve 400 to the inverted configuration. When the outer frame 410 is fully within the outer catheter 403, the positioning catheter 419 can be removed via the apex of the heart and the retrieval assembly 402 can be removed via the transfemoral trans-septal route.

In some embodiments, rather than removing the valve 400 from the heart with the retrieval assembly 402, the retrieval assembly 402 and/or the positioning catheter 419 can be used to reposition the valve 400 within the mitral valve annulus. For example, in some embodiments, the snare member 415 can be used to capture the inner frame 440 of the valve 400 and apply a compressive force to the inner frame 440 to reduce the diameter of the inner frame 440. The valve 400 can then be repositioned via movement of the snare member 415 and/or the positioning catheter 419. In some embodiments, the valve 400 can be partially or fully retracted into the outer catheter 403 and transitioned into the inverted configuration, as shown in FIG. 25C, and then redeployed to the desired location within the left atrium or left ventricle via pulling the tether 436 toward the apex of the heart and/or pushing the snare member 415 and/or the middle catheter 404 distally of the outer catheter 403 and into the left atrium or left ventricle. Upon redeploying from the outer catheter 403, the valve 400 can transition from the inverted configuration to the expanded configuration similarly as described above for the initial deployment of the valve 400.

FIGS. 26-28 are schematic illustrations of a prosthetic mitral valve retrieval system 505 during various stages of a procedure to engage, capture, and remove a prosthetic mitral valve 500 after it has been deployed within a heart H (shown in FIG. 26).

As shown in FIG. 26, the retrieval system 505 can include a retrieval assembly 502. The retrieval assembly 502 can include an outer catheter 503, a middle catheter 504, a snare catheter 506, and a snare member 515. The snare member 515 can be movably disposed within a lumen of the snare catheter 506 and the snare catheter 506 can be movably disposed within a lumen of the middle catheter 504. Similarly, the middle catheter 504 can be movably disposed within a lumen of the outer catheter 503. The outer catheter 503 can have a rigid distal tip. Optionally, in some embodiments, the retrieval system 505 can also include an apical positioning catheter 519.

The retrieval system 505 can engage with a valve assembly (e.g., a prosthetic heart valve) such that the retrieval system 505 can be used to control the position and configuration of the valve assembly. In particular, as shown in FIG. 26, the retrieval system 505 can engage with and retrieve a previously-implanted valve assembly 501 from, for example, a mitral annulus. The valve assembly 501 can include a valve 500 and a tether 536. The valve 500 and the tether 536 can be constructed the same as or similar to, and function the same as or similar to, any of the valves and tethers described herein and in the '305 PCT Application incorporated by reference above. For example, the valve 500 can include an inner frame 540 and an outer frame 510. Additionally, in some embodiments, the inner frame 540 can include a body portion and a tether connecting portion. The tether 536 can be coupled to the inner frame 540 via the tether connecting portion. A strut portion 554 (shown in FIG. 27) (also referred to herein as commissure posts 554) of the inner frame 540 can connect the tether connecting portion to the body portion. The outer frame 510 and the inner frame 540 can be formed with a shape-memory material. As a result, the outer frame 510 can be movably coupled to the inner frame 540 such that the valve 500 can be moved between a biased expanded or deployed configuration, an inverted configuration, and a collapsed or compressed configuration. The expanded configuration allows the valve assembly 501 to function when implanted within the heart H. The valve 500 can be moved to the inverted configuration and/or the compressed or collapsed configuration for delivery of the valve assembly 501 to, or retrieval of the valve assembly 501 from, the heart H of a patient.

More specifically, for delivery of the valve assembly 501 to the heart H via a delivery sheath and/or retrieval of the valve assembly 501 from the heart H via the retrieval assembly 502, the outer frame 510 can be moved to a prolapsed or inverted configuration relative to the inner frame 540 by folding or distally inverting the outer frame 510 via, for example, coupling joints. Prior to being inverted, the outer frame 510 can be in a first position relative to the inner frame 540 in which an open or free end portion is disposed in the same direction as a free end portion of the inner frame 540, as shown in FIGS. 26 and 27. When the outer frame 510 is moved to an inverted configuration, the free end portion of the outer frame 510 is disposed in an opposite direction as the free end portion of the inner frame 540, as shown in FIG. 28.

When in the inverted configuration, an overall length of the valve 500 is increased, but a length of the inner frame 540 and a length of the outer frame 510 remain the same (or substantially the same). In addition, in some instances, depending on the specific configuration of the outer frame 510, an overall outer perimeter or outer diameter of the valve 500 can be smaller when the valve 500 is in the inverted configuration. For example, with the valve 500 in the inverted configuration, the valve 500 can be placed within a lumen of a delivery sheath or the retrieval assembly 502 for delivery to or retrieval from, respectively, the left atrium LA of the heart H. Before inserting the valve 500 into a lumen of the delivery sheath or the retrieval assembly 502, the valve 500 can first be moved to the inverted configuration and then to a collapsed or compressed configuration within the lumen of the delivery sheath or retrieval assembly 502 in which the outer diameter or outer perimeter of the valve 500 is reduced. Because the valve 500 is in the inverted configuration, the valve 500 can be placed within a smaller delivery sheath or retrieval assembly 502 than would be possible if the valve 500 were merely collapsed radially. This is because when the valve 500 is in the biased expanded configuration, the inner frame 540 is nested within an interior of the outer frame 510, and thus the outer frame 510 must be collapsed around the inner frame 540 if merely collapsed radially. Whereas, in the inverted configuration, the inner frame 540 and the outer frame 510 are arranged axially with respect to each other (i.e., the inner frame is not nested within the outer frame 510), such that the outer frame 510 can be collapsed without needing to accommodate all of the structure of the inner frame 540 inside the outer frame 510. In other words, with the inner frame 540 disposed mostly inside or nested within the outer frame 510, the layers or bulk of the frame structures cannot be compressed to as small a diameter. In addition, the valve 500 is more flexible in the inverted configuration. In other words, less force is required to bend the valve 500 for the valve 500 to pass through tortuous vasculature or to make a tight turn (e.g., into the left atrium after passing through the atrial septum Sp to be properly oriented for insertion into the mitral valve annulus or, for retrieval, out of the mitral valve annulus to be properly oriented to pass through the atrial septum Sp). Conversely, if the outer frame 510 and the inner frame 540 are nested, the valve 500 is less flexible and more force is needed to bend the valve 500.

The snare member 515 can be any suitable shape and can include an engagement portion 517. The engagement portion 517 can be extendable from an undeployed configuration (not shown) when disposed within the lumen of the snare catheter 519 to a deployed configuration when disposed outside of the snare catheter 519. In some embodiments, the undeployed configuration of the engagement portion 517 can be a collapsed configuration where the engagement portion 517 is bent, squeezed, or otherwise reduced in diameter to fit into the lumen of the snare catheter 519. The engagement portion 517 can be formed with a shape-memory material and have a biased expanded or deployed configuration such that the engagement portion 517 automatically expands as it is moved out of the lumen of the snare catheter 519.

The engagement portion 517 of the snare member 515 is shaped and sized such that, in the expanded or deployed configuration, the engagement portion 517 can surround and engage with a portion of the inner frame 540 of the valve 500. As shown in FIG. 26, the engagement portion 517 or, alternatively, the entire snare member 515 can be shaped as a coil and sized such that, in the expanded or deployed configuration, the engagement portion 517 can surround the inner frame 540 and engage with the inner frame 540. In such an embodiment, the engagement portion 517 can be formed with a shape-memory material and the coil shape can be elongated in a delivery configuration inside the snare catheter 506. The coil shape can include multiple loops having the same or different diameters when expanded. As the engagement portion 517 is pushed or moved outside the distal end of the snare catheter 506, the portion of the engagement portion 517 outside of the distal end of the snare catheter 506 can transition to an expanded coil configuration. For example, in some embodiments, as a length of the engagement portion 517 is pushed outside of the distal end of the snare catheter 506, the diameter of the engagement portion 517 can enlarge such that the inner frame 540 can be received within the coil shape formed by the engagement portion 517. When the engagement portion 517 is a sufficient size to receive the inner frame 540, the coil can be moved further distally to surround the inner frame 540. Then, the snare catheter 506 can be moved distally relative to the snare member 515 such that the engagement portion 517 is partially withdrawn into a lumen of the snare member 515. As a result, the diameter of the engagement portion 517 can decrease, causing the engagement portion 517 to engage with and apply a compressive force to the inner frame 540, as shown in FIG. 26. Thus, the snare member 515 can be used to control the position and/or diameter of the inner frame 540.

As shown in FIG. 27, the inner frame 540 of the valve 500 can be retracted into the outer catheter 503 via a proximal movement of the snare member 515 while the engagement portion 517 applies a compressive force to the inner frame 540. The snare member 515 can be pulled further proximally such that the outer frame 510 is pulled into abutting contact with the rigid distal tip of the distal end of the outer catheter 503, as shown in FIG. 27. As the snare member 515 pulls the inner frame 540 further proximally relative to the outer catheter 503, the outer frame 510 can be moved (i.e., flipped) into the inverted configuration as a result of the force applied by the rigid distal tip of the outer catheter 503 against the outer frame 510, as shown in FIG. 28. The snare member 515 can continue to be retracted until the outer frame 510 is fully within the outer catheter 503.

In some embodiments, the apical positioning catheter 519 (also referred to herein as “the positioning catheter 519”) can be used to position and/or orient the valve assembly 501 for repositioning and/or retrieval of the valve assembly 501. The positioning catheter 519 can be inserted through the apex Ap of the heart H and translated along the tether 536 (i.e., the tether 536 can be threaded through a lumen of the positioning catheter 519). The positioning catheter 519 can be pushed into abutting contact with the valve 500 such that a portion of the valve is disposed within a lumen of the positioning catheter 519. The positioning catheter 519 can then be used to help move the valve 500 toward the retrieval assembly 502 or reposition the valve 500. In some embodiments, the positioning catheter 519 can engage with the valve 500 such that the positioning catheter 519 can control the movement of the valve 500 in some or all directions (e.g., distal, proximal, rotational, and/or lateral movement). For example, in some embodiments, the positioning catheter 519 can be moved towards the valve 500 along the tether 536 while the tether 536 is simultaneously pulled taut away from the valve 500 such that the valve 500 is positioned in abutting contact with the distal end of the positioning catheter 519. With the tether 536 continuing to be held taut, the positioning catheter 519 can then be used to control the position of the valve 500. In some embodiments, the positioning catheter 519 can be used to aid in transitioning the outer frame 510 between the unbiased, expanded configuration and the inverted configuration. For example, in some embodiments, the positioning catheter 519 can be pushed towards the valve 500 along the tether 536 while the tether 536 is simultaneously pulled taut away from the valve 500 such that the distal end of the positioning catheter 519 can compress or partially collapse a portion of the valve 500, such as, for example, the strut portion 554. The positioning catheter 519 can then assist in pushing the valve 500 toward and/or into the retrieval assembly 502, assisting in providing the force required to transition the valve 500 to the inverted configuration.

In use, the valve assembly 501 can be delivered to a heart H as described above and in the '305 PCT Application. For example, the valve assembly 501 can be placed in the distal end of a delivery sheath in the inverted configuration and the delivery sheath can be introduced through a femoral vein puncture and extended through the femoral vein, through the inferior vena cava IFC, into the right atrium RA, through a trans-septal puncture of the septum of the heart Sp, and into the left atrium LA or left ventricle LV of the heart H. With the distal end portion of the delivery sheath disposed within the left atrium LA or left ventricle LV of the heart H, the valve 500 can be deployed outside a distal end of the delivery sheath. For example, in some embodiments, a pusher device can be used to move or push the valve 500 out of the distal end of the delivery sheath. In some embodiments, the tether 536 can extend through the mitral annulus, through the left ventricle LV, and out of a puncture site at the apex Ap of the heart H. In such embodiments, the valve 500 can be moved out of the delivery sheath by pulling proximally on the tether 536. In some embodiments, the valve 500 can be deployed by pushing with the pusher device and pulling the tether 536. As the valve 500 exits the lumen of the delivery sheath, the outer frame 510 exits first in the inverted configuration. After the outer frame 510 is fully outside of the lumen of the delivery sheath, the outer frame 510 can revert to its expanded or deployed configuration. In some embodiments, the outer frame 510 can revert automatically after fully exiting the lumen of the delivery sheath due to its shape-memory properties. In some embodiments, a component of the delivery sheath or another device can be used to aid in the reversion of the outer frame 510. In some embodiments, the pusher device and/or the tether 536 can be used to aid in reversion of the outer frame 510. The valve 500 can continue to be deployed until the inner frame 540 is fully deployed within the left atrium and the valve 500 is in the expanded or deployed configuration. The valve 500 can then be securely implanted in the mitral annulus. Additionally, the tether 536 of the valve assembly 501 can then be secured to the apex Ap of the heart H with an epicardial pad device, similarly as shown and described with reference to FIG. 24. The delivery sheath and any other delivery instruments can then be removed.

With the valve assembly 501 in the deployed configuration within the mitral annulus, the retrieval system 505 can be used to reposition and/or retrieve the valve assembly 501. In some embodiments, the retrieval assembly 502 can approach the left atrium of the heart transfemorally along the transfemoral trans-septal route (i.e., the same path described above for the delivery of the valve assembly 501). In other words, the outer catheter 503, middle catheter 504, and snare catheter 506 of the retrieval assembly 502 can be introduced through a femoral vein puncture and extended through the femoral vein, through the inferior vena cava IVC, into the right atrium RA, through a trans-septal puncture of the septum Sp of the heart H, and into the left atrium LA of the heart H. In other embodiments, the retrieval assembly 502 can approach the valve assembly 501 transatrially, transjugularly, or along any other suitable path. Additionally, in embodiments in which the tether 536 has been secured to the apex Ap of the heart H via an epicardial pad device, the tether 536 can be separated from the epicardial pad device through any suitable means.

As described above, the valve 500 can be transitioned to the inverted configuration before being moved into the retrieval assembly 502 so that the valve 500 can fit within a smaller diameter retrieval assembly 502 and so that the retrieval assembly 502 and valve 500 can bend more easily when being maneuvered through the body. To transition the valve 500 to the inverted configuration, once the distal end of the retrieval assembly 502 is within the left atrium of the heart, the snare member 515 can be extended outside of the distal end of the snare catheter 506. As the snare member 515 is pushed out of the distal end of the snare catheter 506, the engagement portion 517 of the snare member 515 can transition from the undeployed configuration to the deployed configuration. With the engagement portion 517 in the deployed configuration, the snare member 515 can be moved toward the valve 500 such that the engagement portion 517 surrounds the inner frame 540, as shown in FIG. 2. The engagement portion 517 can then be manipulated such that the engagement portion 517 grasps the inner frame 540 (e.g., the engagement portion 517 can be reduced in diameter to securely engage with the inner frame 540). When the engagement portion 517 is securely engaged with the inner frame 540, the engagement portion 517 can be further manipulated to apply a compressive force to reduce the diameter of the inner frame 540 to a diameter sufficiently small to fit within the middle catheter 504.

While compressing the inner frame 540, the snare member 515 can be retracted proximally relative to the snare catheter 506 and/or the snare catheter 506 can be retracted proximally relative to the middle catheter 504. As a result, at least a portion of the inner frame 540 can be pulled into a lumen of the middle catheter 504, as shown in FIG. 27. The snare member 515, snare catheter 506, and middle catheter 504 can then be pulled proximally relative to the outer catheter 503 such that the outer frame 510 transitions to the inverted configuration, as shown in FIG. 28. More specifically, the proximal movement of the inner frame 540 can cause the outer frame 510 to be pulled against the rigid tip of the distal end of the outer catheter 503. As the inner frame 540 is pulled further proximally, the rigid tip of the outer catheter 503 can force the outer frame 510 to flip into the inverted configuration. The snare member 515, snare catheter 506, and middle catheter 504 can then continue to be retracted until the outer frame 510 is fully within the outer catheter 503.

Optionally, the positioning catheter 519 can be used to aid in positioning and orienting the valve assembly 501 for repositioning and/or retrieval. In such embodiments, as shown in FIG. 26, the positioning catheter 519 can be inserted through the apex Ap of the heart H and translated along the tether 536. With the tether 536 pulled taut through the positioning catheter 519, the positioning catheter 519 can be moved into abutting contact with the valve 500 such that the positioning catheter 519 can be used to help move the valve 500 toward and/or into the retrieval assembly 502. Additionally, in some embodiments, the positioning catheter 519 can be used to aid in transitioning the outer frame 510 between the expanded or deployed configuration and the inverted configuration. For example, as shown in FIGS. 27 and 28, the positioning catheter 519 can push the inner frame 540 and/or a central portion of the outer frame 510 into the outer catheter 503 to assist the outer frame 510 in transitioning (i.e., flipping) to the inverted position. Additionally, in some embodiments, the positioning catheter 519 can be pushed towards the valve 500 such that the positioning catheter 519 compresses or partially collapses a portion of the valve 500, such as, for example, the strut portion 554. The positioning catheter 519 can then assist in pushing the valve 500 toward and/or into the retrieval assembly 502 by assisting in providing the force required to transition the valve 500 to the inverted configuration. When the outer frame 510 is fully within the outer catheter 503, the positioning catheter 519 can be removed via the apex Ap of the heart H and the retrieval assembly 502 can be removed via the transfemoral trans-septal route.

In some embodiments, rather than removing the valve 500 from the heart H with the retrieval assembly 502, the retrieval assembly 502 and/or the positioning catheter 519 can be used to reposition the valve 500 within the mitral valve annulus. For example, in some embodiments, the snare member 515 can be used to capture the inner frame 540 of the valve 500 and apply a compressive force to the inner frame 540 to reduce the diameter of the inner frame 540. The valve 500 can then be repositioned via movement of the snare member 515 and/or the positioning catheter 519. In some embodiments, the valve 500 can be partially or fully retracted into the outer catheter 503 and transitioned into the inverted configuration, as shown in FIG. 28, and then redeployed to the desired location within the left atrium LA or left ventricle LV via pulling the tether 536 toward the apex Ap of the heart H and/or pushing the snare member 515 and/or the middle catheter 504 distally of the outer catheter 503 and into the left atrium LA or left ventricle LV. Upon redeploying from the outer catheter 503, the valve 500 can transition from the inverted configuration to the expanded configuration similarly as described above for the initial deployment of the valve 500.

FIG. 29 is a flowchart illustrating a method of retrieving an implanted prosthetic mitral heart valve, according to an embodiment. The method includes at 602, inserting a retrieval assembly through the femoral vein and into a heart of a patient until a distal end portion of the retrieval assembly is disposed in an atrium of the heart. The prosthetic heart valve can be formed with a shape-memory material. In some embodiments, the prosthetic heart valve is a prosthetic mitral valve and the inserting includes inserting the retrieval assembly through a septum of the heart and into a left atrium of the heart. The retrieval assembly can include an outer catheter, a middle catheter, a snare catheter, and a snare member. The snare member can be moved distally out of a lumen of the retrieval assembly into engagement with an inner frame of the prosthetic heart valve, at 604. For example, the snare member can be moved distally out of a lumen of the snare catheter. At 606, the retrieval assembly can be manipulated to invert an outer frame of the prosthetic mitral valve such that the prosthetic heart valve can be collapsed and retracted into a lumen of the retrieval assembly. In some embodiments, a positioning catheter can be inserted through the apex of the heart and moved into engagement with a portion of the prosthetic heart valve (e.g., a portion extending into a ventricle or closest to the ventricle of the heart) to assist in positioning and inverting the prosthetic valve, at 608.

Although the specific embodiments described herein refer to devices and methods for retrieving and repositioning a prosthetic mitral valve, the devices and methods can also be used to retrieve and reposition other prosthetic heart valves, such as, for example, tricuspid heart valves.

While various embodiments have been described above, it should be understood that they have been presented by way of example only, and not limitation. Where methods described above indicate certain events occurring in certain order, the ordering of certain events may be modified. Additionally, certain of the events may be performed concurrently in a parallel process when possible, as well as performed sequentially as described above.

Where schematics and/or embodiments described above indicate certain components arranged in certain orientations or positions, the arrangement of components may be modified. While the embodiments have been particularly shown and described, it will be understood that various changes in form and details may be made. Any portion of the apparatus and/or methods described herein may be combined in any combination, except mutually exclusive combinations. The embodiments described herein can include various combinations and/or sub-combinations of the functions, components, and/or features of the different embodiments described. 

What is claimed is:
 1. An apparatus, comprising: a retrieval assembly including an outer catheter, a middle catheter and a snare catheter, and a snare member movably disposable within a lumen of the snare catheter, the snare catheter movably disposable within a lumen of the middle catheter, the middle catheter movably disposable within a lumen of the outer catheter, the snare member including an engagement portion that can be moved between a collapsed configuration when disposed within the lumen of the snare catheter and an expanded configuration when moved outside the lumen of the snare catheter, the engagement portion configured to engage and surround at least a portion of an inner frame of a prosthetic heart valve implanted within a heart such that the prosthetic heart valve can be repositioned or removed from the heart with the apparatus.
 2. The apparatus of claim 1, wherein the engagement portion is formed with a shape-memory material such that the engagement portion automatically moves to the expanded configuration when moved outside of the lumen of the snare catheter.
 3. The apparatus of claim 1, wherein the outer catheter has a rigid distal tip.
 4. The apparatus of claim 1, wherein the engagement portion of the snare member includes at least one loop configured to surround at least a portion of the prosthetic heart valve.
 5. The apparatus of claim 1, wherein the engagement portion of the snare member has a coil shape and is configured to surround at least a portion of the prosthetic heart valve.
 6. The apparatus of claim 5, wherein the coil shape includes multiple loops having the same diameter when expanded.
 7. The apparatus of claim 5, wherein the coil shape includes multiple loops having different diameters when expanded.
 8. The apparatus of claim 1, further comprising: a positioning catheter having a distal end, the distal end configured to engage a portion of the prosthetic heart valve such that the positioning catheter can move the prosthetic heart valve toward the outer catheter of the retrieval assembly.
 9. The apparatus of claim 8, wherein the positioning catheter defines a lumen, a tether coupled to the prosthetic heart valve can be movably disposed within the lumen of the positioning catheter.
 10. The apparatus of claim 8, wherein the distal end of the positioning catheter is configured to be inserted into and movably disposed within the outer catheter.
 11. A system, comprising: a prosthetic heart valve having an outer frame, and inner frame disposed within the outer frame, and a valve assembly coupled to the inner frame, the outer frame being invertible relative to the inner frame; and a retrieval assembly including an outer catheter, a middle catheter and a snare catheter, and a snare member movably disposable within a lumen of the snare catheter, the snare catheter movably disposable within a lumen of the middle catheter, the middle catheter movably disposable within a lumen of the outer catheter, the snare member including an engagement portion that can be moved between a collapsed configuration when disposed within the lumen of the snare catheter and an expanded configuration when moved outside the lumen of the snare catheter, the engagement portion configured to engage and surround at least a portion of the inner frame of the prosthetic heart valve implanted within a heart such that the prosthetic heart valve can be repositioned or removed from the heart with the retrieval assembly.
 12. The system of claim 11, wherein the engagement portion is formed with a shape-memory material such that the engagement portion automatically moves to the expanded configuration when moved outside of the lumen of the snare catheter.
 13. The system of claim 11, wherein the outer catheter has a rigid distal tip.
 14. The system of claim 11, wherein the engagement portion of the snare member includes at least one loop configured to surround at least a portion of the prosthetic heart valve.
 15. The system of claim 11, wherein the engagement portion of the snare member has a coil shape and is configured to surround at least a portion of the prosthetic heart valve.
 16. The system of claim 15, wherein the coil shape includes multiple loops having the same diameter when expanded.
 17. The system of claim 15, wherein the coil shape includes multiple loops having different diameters when expanded.
 18. The system of claim 11, further comprising: a positioning catheter having a distal end, the distal end configured to engage a portion of the prosthetic heart valve such that the positioning catheter can move the prosthetic heart valve toward the outer catheter of the retrieval assembly.
 19. The system of claim 18, wherein the positioning catheter defines a lumen, a tether coupled to the prosthetic heart valve can be movably disposed within the lumen of the positioning catheter.
 20. The system of claim 18, wherein the distal end of the positioning catheter is configured to be inserted into and movably disposed within the outer catheter. 